Susan Collins is one of five senators to watch in the gun-control debate

WASHINGTON — Vice President Joe Biden is promising to produce a package of proposals aimed at curbing gun violence by the end of the month, a move that will trigger a major legislative brouhaha on Capitol Hill in the coming weeks.

Biden, a veteran of congressional slugfests, made clear in remarks Wednesday that he was both open to compromise and committed to action.

“This is a problem that requires immediate attention,” Biden said. “I want to make clear that we’re not going to get caught up in the notion that, unless we can do everything, we’re going to do nothing.”

While all 535 members of Congress will have something to say — they are politicians, after all — on whatever Biden and his task force propose, some members matter more than others.

Here, a list of five senators who will play key roles in determining the fate of any gun legislation. (The senators listed below — in alphabetical order — are gathered from our own observations as well as the thoughts of connected operatives in both parties.)

Michael Bennet (Colorado): He is the head of the Democratic Senatorial Campaign Committee, the organization charged with re-electing the 21 incumbents up for re-election in November 2014. Many of the senators facing the toughest races — Tim Johnson in South Dakota, Jay Rockefeller in West Virginia, Mary Landrieu in Louisiana, Kay Hagan in North Carolina — represent states where gun ownership is the rule not the exception. Bennet will need to run interference for this group, making sure that the White House doesn’t leave them out on a political limb that their Republican opponent can easily saw off.

Susan Collins (Maine): The retirement of Sen. Olympia Snowe, R-Maine, and defeat of Sen. Scott Brown, R-Mass., makes Collins the most high-profile Republican moderate in the world’s greatest deliberative body. In the aftermath of the Newtown, Conn., elementary school shootings, Collins released a statement insisting that “while denying the constitutional rights of law-abiding citizens won’t change the behavior of those intent on using firearms for criminal purposes, I wholeheartedly agree that we must examine what can be done to help prevent gun violence.” What that means in terms of specific sorts of legislative measures she would support is anyone’s guess.

Dianne Feinstein (California): The Democrat has long been an active voice for more gun control, stemming from her personal experience with gun violence. (In the late 1970s, Feinstein became mayor of San Francisco after Mayor George Moscone and Supervisor Harvey Milk were murdered by a former colleague.) Feinstein has pledged to introduce a version of the assault weapons ban in the 113th Congress. That ban expired in 2004. Feinstein is likely to be in the middle of any attempted legislative solution and will be a major figure pushing hard for the Obama administration to do more rather than less on restricting

Joe Manchin (West Virginia): In his 2010 Senate race, the Democrat ran an ad that showed him shooting — literally, shooting — President Barack Obama’s cap and trade bill. In the wake of the Newtown shootings, Manchin said he was open to further dialogue on guns in society but offered few specifics about what he might be for or against. If Biden and the White House can convince someone like Manchin to sign on to their proposal, it would be a major symbolic win. If not, the opposite holds true.

Mitch McConnell (Kentucky): In the aftermath of the fiscal cliff negotiations, we coined the GOP leader the “Red” of the Senate (after Morgan Freeman’s “Shawshank Redemption” character, a man who knows how to get things). Given the proof we have that McConnell and Biden know how to cut deals, it seems virtually certain that any major — or even minor — deal on guns will feature McConnell as a prime player. Never forget that McConnell has his own politics to keep an eye on in a state that is decidedly friendly to gun rights. McConnell’s numbers in the state are not great, but a GOP primary challenge seems unlikely and no major Democrats are making noise about the contest — yet.

Cillizza writes The Fix, a politics blog for the Washington Post, and Blake is a frequent contributor to it.